In recent years, the employment of non-lethal weapons has proven increasingly effective in dealing with adversaries in a variety of law enforcement, corrections, military, and physical security scenarios. In these areas, the goal of protection personnel in most confrontations is to employ the lowest level of force necessary to control the situation. Avoidance of collateral damage is increasingly critical for humanitarian and public policy reasons. The possible levels of response force fall ranging from verbal warnings, escalating to use of lethal weapons such as firearms. The possibility of permanent injury or unintentional death increases as response level increases. Also, as the level of force applied increases, adversaries will often escalate their response thereby increasing the risk of injury to the security personnel. Any means to minimize the level of interaction between the protector and the aggressor is therefore of great value to security personnel and their adversaries alike. Consequently security protection personnel need a response that assures their personal safety and eliminates the threat of collateral damage to the maximum extent possible.
Ultra-bright light laser sources utilizing coherent light are claimed to offer a means to control escalation of confrontations between security personnel and adversaries. These light sources provide four levels of physical interaction with adversaries at the “soft” end of the force continuum: psychological impact such as distraction and fear; temporarily impaired vision (blindness); physiological response to the light such as disorientation and nausea; and reduced ability to perform hostile acts such as throwing objects, attacking, or aiming firearms. In addition, the adversaries' response to the illumination can provide security personnel with threat assessment in terms of intent and resolve. Examples, of such devices are described in U.S. Pat. Nos. 5,685,636, 6,007,218 and 7,040,780.
Within the various application areas, there are many scenarios where a non-lethal response with ultra-bright lights can be beneficial. These include perimeter protection for government and industrial facilities, apprehension of armed and unarmed but violent subjects, protection from suspected snipers, protection from assailants, and crowd/mob control. Prison guards need non lethal options in a variety of situations including cell extractions, breaking up fights, and controlling disturbances. Another important class of scenarios is that which limit the use of potentially lethal weapons because innocent people are present. These include hostage situations, hijackings, protection of political figures in crowds, airport security, and crowd control.
Collateral damage when using firearms or explosives on the battlefield is an increasing problem. In time-critical scenarios, such as raids on hostile facilities or criminal hideouts, where even a few seconds of distraction and visual impairment can be vital to the success of the mission, visual countermeasures can enhance the capabilities of law enforcement personnel.
Present devices utilizing coherent bright light sources are capable of a range of effects on human vision which depend primarily on the wavelength, beam intensity at the eye (measured in watts/square centimeter), and whether the light source is pulsed or continuous-wave coherent light. There are three types of non-damaging effects on vision using these sources; glare, flashblinding and physiological disorientation. All of these technologies have application disadvantages.
The glare effect is a reduced visibility condition due to a bright source of light in a person's field of view. It is a temporary effect that disappears as soon as the light source is extinguished, turned off, or directed away from the subject. The light source used must emit light in the visible portion of the spectrum and must be continuous or flashing to maintain the reduced-visibility glare effect. The degree of visual impairment due to glare depends on the brightness of the light source relative to ambient lighting conditions. The disadvantage is that the aggressor is still capable of inflicting harm and is not incapacitated.
The flashblinding effect is a reduced visibility condition that continues after a bright source of light is switched off. It appears as a spot or afterimage in one's vision that interferes with the ability to see in any direction. The nature of this impairment makes it difficult for a person to discern objects, especially small, low-contrast objects or objects at a distance. The duration of the visual impairment can range from a few seconds to several minutes. The visual impairment depends upon the brightness of the initial light exposure and the ambient lighting conditions and the person's visual objectives. The major difference between the flashblind effect and the glare effect is that visual impairment caused by flashblind remains for a short time after the light source is extinguished, whereas visual impairment due to the glare effect does not. The disadvantage it that the use of flash grenades can blind the user as well as bystanders and dispensing methods may present fire or explosive hazards. Phosphorus grenades that explode on impact, creating lots of noise, bright white light, have the drawback that they produce high levels of heat capable of inflicting severe burns.
Physiological disorientation occurs in response to a flashing or strobe light source. It is caused by the attempt of the eye to respond to rapid changes in light level or color. For on-and-off flashing, the pupil of the eye is continually constricting and relaxing in response to the contrasting light intensity reaching the eye. In addition, differing colors as well as differing light intensities cause the same effect. The disadvantage is epileptic fits may result and permanent neurological damage has been reported. The National Society for Epilepsy states “Around one in two hundred people have epilepsy and of these people only 3-5% have seizures induced by flashing lights. Photosensitivity is more common in children and adolescents and becomes less common from the mid twenties onwards.”
Other devices such as electromagnetic weapons like the Vehicle-Mounted Active Denial System or VMADS being developed by Raytheon Missile Systems fires a focused, millimeter wave energy beam to induce an intolerable heating sensation. The energy penetrates less than 1/64 of an inch into the skin and the sensation ceases when the target moves out of the beam. Unfortunately, such a device does not incapacitate or disable the aggressor.
Thermal guns raise the agressor's body temperature to between 105 and 107 degrees Fahrenheit, creating an instant and incapacitating fever. The magnetophosphene gun can make a subject “see stars” by delivering what feels like a blow to the head. Such a device has the potential to do brain and bodily damage due to excessive heat.
Eye-Safe light laser security devices such as those described in U.S. Pat. Nos. 5,685,636 and 6,007,218 employ a single coherent light laser or bank of lasers as the light source. The laser can operate at any narrow wavelength band between 400 and 700 nanometers and provide either continuous or repetitively pulsed (on-off flashing) light. Although effective at stopping an aggressor, these types of non-lethal security devices could benefit from improvements in the areas of safety in use, overall effective, susceptibility to countermeasures, and cost. The disadvantage of coherent light lasers is that they produce a very narrow beam that is difficult to target and manage its intensity to avoid permanent eye damage. Furthermore the laser is susceptible to counter measures such as filtered goggles that are wave specific. A fixed laser wavelength has the added disadvantage of not shifting to correspond to the shift in sensitivity from day to night (Photopic curve to Scotopic curve).
Consequently there is a need in the industry for a non-lethal, visual security device that does not cause blindness or retinal damage, present a burn hazard, pose a fire or explosive hazard, cause seizures or brain damage, cause permanent harm to the target or others, that incapacitates the aggressor so that they may be easily apprehended, is capable of low cost manufacture, is relatively resistant to countermeasures, may be easily directed at one or more aggressors simultaneously, can incapacitate a target at great distances and renders the aggressor incapable of further aggression for a period of time to enable capture.